The function of kidneys, which are glandular organs located in the upper abdominal cavity of vertebrates, is to filter blood and remove waste products. Specifically, kidneys separate water and waste products of metabolism from blood and excrete them as urine through the bladder. Chronic renal failure is a disease of the kidney in which the kidney function breaks down and is no longer able to filter blood and remove waste substances. Should certain toxic waste substances not be removed from the blood, the toxic substances may increase to lethal concentrations within the body.
Hemodialysis is a life-sustaining treatment for patients who have renal failure. Hemodialysis is a process whereby the patient's blood is filtered and toxins are removed using an extracorporeal dialysis machine. For hemodialysis to be effective, large volumes of blood must be removed rapidly from the patient's body, passed through the dialysis machine, and returned to the patient. A number of operations have been developed to provide access to the circulation system of a patient such that patients may be connected to the dialysis machine.
For example, a commonly performed hemodialysis access operation is a subcutaneous placement of an arteriovenous graft, which is made from a biocompatible tube. The biocompatible tube can be made of, for instance, a fluoropolymer such as polytetrafluoroethylene. One end of the tube is connected to an artery while the other end is connected to a vein. The arteriovenous graft is typically placed either in the leg or arm of a patient.
Blood flows from the artery, through the graft and into the vein. To connect the patient to a dialysis machine, two large hypodermic needles are inserted through the skin and into the graft. Blood is removed from the patient through one needle, circulated through the dialysis machine, and returned to the patient through the second needle. Typically, patients undergo hemodialysis approximately four hours a day, three days a week.
Various problems, however, have been experienced with the use of an arteriovenous graft. For example, arterial steal occurs when excessive blood flow through the arteriovenous graft “steals” blood from the distal arterial bed. Arterial steal can prevent the proper supply of blood from reaching the extremity of a patient.
To address such problems, systems and processes have been deployed which can minimize or prevent complications by closing the arteriovenous graft when hemodialysis is not taking place. An example of one such system is described in U.S. Pat. No. 7,025,741 entitled “Arteriovenous access valve system and process”, which is hereby incorporated by reference herein in its entirety for all purposes. These systems and processes utilize valves, such as balloon valves, to force closure of one or more portions of an arteriovenous graft by pressing the arteriovenous graft walls together.
However, such implanted valve systems typically require that the valves be actuated using one or more hypodermic needles. For example, for a system including two balloon valves (e.g., a valve positioned at each end of the arteriovenous graft), two separate needles must be used inserted through the patient's skin and into corresponding injection ports associated with the valves to allow the balloons to be inflated and deflated. The use of such needles significantly adds to the ongoing costs of performing hemodialysis processes. In addition, the needles add to the discomfort level of the patient as the hemodialysis process is being performed.
Accordingly, a needle-free, arteriovenous access valve system would be welcomed in the technology.